Floating deck for storage tank

ABSTRACT

A FLOATING DECK FOR USE IN LIQUID STORAGE TANKS IS PROVIDED IN WHICH A PLURALITY OF INDIVIDUALLY BUOYANT FLOATS FILLED WITH A POLYMERIC MATERIAL ARE USED TO KEEP THE DECK AFLOAT.

United States Patent [72} Inventor Lou C. Creith Allentown, Pa. [21]Appl. No. 811,878 [22] Filed Apr. 1, 1969 [45] Patented June 28, 1971[73] Assignee Olin Mathieson Chemical Corporation [54] FLOATING DECK FORSTORAGE TANK 7 Claims, 4 Drawing Figs. [52] US. Cl 220/26 [51] Int. ClB6511 87/18 [50] Field of Search... 220/26, 26(5), 26(D), 26(Si) [56]References Cited UNITED STATES PATENTS 2,036,372 4/1936 Stough 220/26(S)2,586,856 2/l952 Orr et al. 220/26 Primary Examiner-Joseph R. LeclairAssistant ExaminerJames R. Garrett Attorneys-Richard S. Strickler,Robert H. Bachman, Donald R. Motsko and Thomas P. ODay ABSTRACT: Afloating deck for use in liquid storage tanks is provided in which aplurality of individually buoyant floats filled with a polymericmaterial are used to keep the deck afloat.

PATENTEU JUN28 ml SHEET 2 0F 2 FIG '3 FIG -4 INVENTOR LOU C. CHE/TH $44MZMM- A'ITORNEY FLOATING DECK FOR STORAGE TANK This invention relates ingeneral to an improvement in floating decks for use within a liquidstorage tank, and more par ticularly to such a deck having improvedfloatability apparatus.

Floating decks of many types and forms have been proposed and used intanks designed for the storage of various liquids. Such a deck may formthe roof of the particular storage tank, or may be a separate memberwithin a tank having a fixed roof. In either case, the deck floatssubstantially horizontally on or slightly above the surface of theliquid stored and moves upwardly and downwardly with the surface as thevolume of the liquid stored varies. Thus, protection is afforded to theliquid stored from the environment above the deck; additionally,evaporation from the area below the deck is retarded.

Many floating decks suffer from the significant disadvantage of beingrelatively expensive to fabricate and to erect within the storage tankto be protected.

One form of a deck which has been proposed utilizes a plurality ofindividually, air-filled buoyant floats to keep the deck afloat. Thissuffers from the disadvantage that the air-filled buoyant floats aresusceptible to collapse at low temperatures. Also, by their natureoptimum buoyance requires a great many of these floats.

Accordingly, it is a principal object of the present invention toprovide an improved floating deck for use in liquid storage tanks.

A further object of the present invention is to provide an improvedfloating deck which overcomes the prior disadvantages, some of which arereferred to hereinabove.

A still further object of the present invention is to provide a floatingdeck with improved buoyancy characteristics which is relatively easy tofabricate and relatively easy to install and which provides the numerousadvantages referred to in the ensuing specification.

Further objects and advantages of the present invention will appear fromthe following specification.

In accordance with the present invention it has now been found that theforegoing objects and advantages may be readily obtained and an improvedfloating deck provided. The floating deck of the present inventioncomprises:

A. a substantially horizontal framework;

B. a plurality of metal floats supported by said framework and mountedto extend downwardly in the liquid stored, said floats having a bottomportion adapted to extend into the liquid, 2. side portions extendingupwardly from said bottom por- Hon,

3. a cover portion affixed to said sides and enclosing a space withinsaid floats, and

4. a polymeric foam, preferably a rigid polyurethane foam,

contained within said space,

C. a rigid material substantially impervious to the liquid storedsupported by said framework in a substantially horizontal plane to coversaid liquid; and

D. said floats having sufficient buoyance to cause said framework andsaid material to float above the level of the liquid stored.

The present invention also comprises as an additional improvement theprovision of a corrugated material as the rigid material impervious tothe liquid stored, preferably corrugated metal. This provides numerousadvantages in any floating deck, some of which will be seen hereinafter.

The features of the present invention will be more readily apparent byreference to the ensuing specification with particular reference to thedrawings which form a part thereof in which:

FIG. I is a perspective view of one form of tank in which a deckaccording to the instant invention may be employed, with a portion ofthe tank wall shown broken away to expose the deck in the interiorthereof;

FIG. 2 is a perspective view of the deck of the present inventionremoved from the tank with a portion of the upper corrugated surfacebroken away in order to expose the lower surface more clearly;

HO. 3 is a sectional view through lines 3-3 of FIG. 2; and

FIG. 4 is a sectional view through lines 4-4 of FIG. 2.

While it is to be understood that the instant floating .deek may beemployed in any type or shape of vertical walled storage tank, FIG. 1illustrates by way of example a floating deck 10 in use in a cylindricalstorage tank 11 having a fixed roof l2 and a center pole 13. Naturally,the floating deck of the present invention may be used in larger storagetanks requiring a plurality of poles 13. The tank 11 contains liquid 14which may be of any type normally stored in this type of storage tank.

Column negotiating device 15 is shown schematically and may be ofconventional construction or may be of the type shown in US. Pat. No.3,409,165. Naturally, other conventional appurtenances may be provided,not shown in the attached drawings, such as a tank manhole, antistaticcables, gauging funnel, tank inlet pipe, antirotational cables, overflowand air vents.

The floating deck 10 effectively covers the surface of the liquid 14 bya substantially horizontal framework supporting a number of buoyantfloats 20 and rigid sheets 21.

The specific construction of the deck will be detailed below. It shouldbe understood that all components of the deck disclosed are of amaterial impervious and impermeable to the liquid stored. Certainmaterials may, for example, be a light metal such as aluminum, a plasticmaterial or a fabric coated with suitable material such as a plasticmaterial.

Considering first the construction of the framework which supports allother components, the framework is generally designated by 16. Theframework 16 has an annular peripheral ring 22 which is spaced from thetank wall. The framework also has a grid of beams 23. It should be notedthat in view of the strength provided by the floats of the presentinvention, it is not necessary to provide crossbeams in order to givethe floating deck structural strength. Naturally, in very large tanks,crossbeams or cross girders or partial crossbeams may be provided ifdesired in order to obtain still further strength. The peripheral ring22 conforms in configuration to the perimeter of the tank 11 but isspaced laterally inwardly from the tank walls. Within ring 22 are aplurality of spaced coplanar beams 23. The shape of the beams 23 are notcritical and may be either of an L-shape, T-shape, I-shape or C-shape orany other convenient shaped cross section. The beams 23 transverse theentire area enclosed by ring 22 and are interconnected to ring 22 atintersecting points 24 by any suitable means such as bolts or rivets.

The beams 23 and ring 22 should naturally be formed of a metal such asaluminum.

To form a seal between the ring 22 and the interior walls of the tank11, while allowing for irregularities in the tank walls as the deckmoves upwardly or downwardly, a suitable flexible but resilient sealingmeans 25 is attached about the periphery ofa ring 22 as by nut 26 andbolt 27.

As indicated hereinabove, sheets 21 are supported by the framework in asubstantially horizontal plane. The sheets 21 should be of a rigidmaterial substantially impervious to the liquid stored, such as aluminumsheet. In the preferred embodiment, as shown in the drawings, the sheets21 cover the entire area enclosed by ring 22. If desired, the sheets 21need not cover the floats. The floats are covered themselves and areimpervious to the liquid stored. Hence, one may readily provide one rowof floats and one row of sheets in an alternating manner. In thepreferred embodiment, however, the sheets completely cover the entirearea enclosed by ring 22 for simplicity ofconstruction and foradditional strength.

Sheets 21 are attached to ring 22 by any convenient method, such as nut28 and bolt 29. ln addition, a sealing means 30 is preferably providedat the juncture of sheets 21 and ring 22, such as a closed cell,flexible sponge.

The material used for sheets'2l may be flat or corrugated. It ispreferred in accordance with the present invention to utilize acorrugated sheet as shown in the drawings. This provides the advantageof additional strength and also improves the efficiency of any floatingdeck. Hence, a corrugated surface which completely covers both theliquid and the floats would readily provide for water drains, shownschematically in H0. 3 at 31, in case of a roof leak since drains couldbe readily provided at the end of each line of corrugations and thesurface may readily be drained.

Between certain portions of beams 23 are inserted a plurality of thefloats 20. The float 20 is designed to be individually buoyant and has abottom portion 40 adapted to extend into the liquid, side portions orsidewalls 41 extending upwardly from bottom portion 40 and integraltherewith, and integral flanges 42 extending laterally from the upperedges of the sides 41. A cover portion 43 is affixed to flanges 42enclosing a space within said float 20. The float 20 is filled with apolymeric foam 44 contained within said space. In the preferredembodiment the space is filled with rigid polyurethane foam. A specificillustration of materials which may be used is to provide a rigidpolyurethane foam weighing approximately 3 pounds per cubic foot insidea float with a rectangular cross section approximately 4 inches X1 8inches and 8 inches long. A plurality of these floats on the undersidesurface of the deck would provide the necessary strength to supportpersonnel walking on top of the deck. This foam material has been foundto be satisfactory at a temperature of 65 F. and the deck may readily bewalked on while floating on gasoline or other similar materials.

In use, the bottom 40 of float 20 extends downwardly into the liquidstored with cover 43 and flanges 42 being attached to beams 23 andsheets 21 by any desired means, such as bolts 45 and nuts 46. Naturally,the method of attachment of the floats may be modified to suit theparticular deck construction.

Hence, it can be readily seen that the floating deck of the presentinvention provides numerous advantages. In view of the structuralstrength of the filled floats of the present invention, it is possibleto eliminate many of the crossbeams heretofore required. Furthermore,the floating deck of the present invention is readily fabricated at areasonable cost. The increased buoyance of the filled floats of thepresent invention provides an additional added advantage and readilyenables the floating deck of the present invention to be walked on bypersonnel.

Furthermore, the corrugated surface of the deck provides an addedadvantage against leakage as indicated hereinabove and allows dispersalof fluid in case of accidental submersion of part of the deck.

An additional advantage of the present invention resides in theprovision of adjustable legs 50. These are provided to prevent the deckfrom reaching the bottom of the tank when the tank is empty. As shown inthe drawings, a preferred construction for adjustable legs 50 comprisesannular sleeve connected to beams 23 by any desired means. Rod or pipe52 of greater length than sleeve 51 fits inside sleeve 51 and extendsdownwardly towards the bottom of the tank. Pipe 52 is provided with aplurality of pinholes for adjusting the height of leg portion 53. Twosuch pinholes are shown in the drawings, pinhole 54 for low position andpinhole 55 for high position. Thus, if the low position is desired, pin56 may be inserted in pinhole 54 as shown, with sleeve 51preventingmovement of pipe 52. if the high position is desired, pin 56 is removedfrom pinhole 54 while the deck is in a higher position, pipe 52 is movedso that pipe pinhole 55 lines up with sleeve pinhole 57 and pin 56 isinserted through pinholes 55' and 57. Flange 58 prevents relativemovement of pipe 52. Naturally, more than two such pinholes may beprovided.

Further advantages of the present invention will be readily apparent toone skilled in the art especially in view of the simplicity and strengthof the present floating deck.

This invention may be embodied in other forms or carried out in otherways without departing from the spirit or essential characteristicsthereof. The present embodiment is therefore to be considered as in allrespects illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims, and all changes which comewithin the meaning and range of equivalency are intended to be embracedtherein.

lclaim:

l. A floating deck for use in a storage tank containing a liquid,comprising:

A. a substantially horizontal framework, said framework comprising,

1. an annular peripheral ring spaced from the tank wall,

2. a flexible flange affixed to the frame and extending substantiallyhorizontally outwardly therefrom to contact the wall, and

3. a plurality of spaced coplanar beams traversing the area enclosed bysaid ring, said beams being connected to said ring;

B. a plurality of legs supported by said framework;

C. a plurality of metal floats supported by said framework and mountedto extend downwardly into the liquid stored, said floats having;

1. a bottom portion adapted toextend into the liquid,

2. side portions extending upwardly from said bottom portion,

3. a cover portion affixed to said sides enclosing a space within saidfloats, and I 4. a rigid polymeric foam filling said space;

D. a rigid sheet material substantially impervious to the liquid storedsupported upon and covering said framework in a substantially horizontalplane to cover said liquid; and

E. said floats having sufficient 'buoyancy to cause said framework andsaid material to float above the level of the liquid stored.

2. 'A floating deck according to claim 1 wherein said polymeric foam isa rigid polyurethane foam.

3. A floating deck according to claim 1 wherein said rigid materialcovers said liquid and said floats.

4. A floating deck according to claim 1 wherein said legs areadjustable.

5. A floating deck according to claim 1 wherein said rigid material ismetal.

6. A floating deck according to claim 5 wherein said rigid material iscorrugated metal.

7. A floating deck according to claim 6 wherein said corrugated materialincludes drainage means.

